linux-kernel - Re: [PATCH v2 2/6] sched/rt: Optimize select_task_rq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20141104075237.4eb9b5e6@gandalf.local.home>
Date:	Tue, 4 Nov 2014 07:52:37 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	"pang.xunlei" <pang.xunlei@...aro.org>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...il.com>
Subject: Re: [PATCH v2 2/6] sched/rt: Optimize select_task_rq_rt() for
 non-RT curr task

On Tue,  4 Nov 2014 19:13:01 +0800
"pang.xunlei" <pang.xunlei@...aro.org> wrote:

> When selecting the cpu for a waking RT task, if curr is a non-RT
> task which is bound only on this cpu, then we can give it a chance
> to select a different cpu(definitely an idle cpu if existing) for
> the RT task to avoid curr starving.

Absolutely not! An RT task doesn't give a crap if a non RT task is
bound to a CPU or not. We are not going to migrate an RT task to be
nice to a bounded non-RT task.

Migration is not cheap. It causes cache misses and TLB flushes. This is
not something that should be taken lightly.

Nack

-- Steve

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/